In which way?
Horn mouth could be lots bigger (~ 1100 cm2) but that should not be a show stopper, only more ripple. The "natural alignment" for the FE167e is approx 16.3 liter, Bessel alignment is approx 14.6 liter, Bullock alignment is approx 17 liter and Keele Hoge alignment is approx 19.8 liter. I feel the size of the chamber at approx 16 liter is workable. It has more promise than the Fostex BK-16 horn which needs a lower Qts driver to get it best results.
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Badly IMO for the same reason Dave mentions. Too small for the tuning with the 167; it'll end up damped to the point of having little actual gain.
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DNA+ with FE167E - corner loaded
Concerns that the DNA box may be a little small and that the bass gain from the horn may not be enough are true. However, it is not totally a lost cause if you are willing to use the DNA in a corner and use a BSC to sacrifice some sensitivity. I made the internal width of the whole speaker wider by 2.5 inches (10.5 in wide internally) and added a 1.2mH & 10ohm BSC. This is kind of a small speaker and it helps to raise it off the floor on a 2 ft tall stand which places the driver height at about 40 inches and helps to reduce a floor bounce cancellation. Also, add light stuffing in the channel immediately after the round throat, and a light amount in the horn channel at the bottom 'gooseneck' where it goes down up and down. No stuffing in the long passage from top to bottom or the mouth area. Line 3 of the walls inside the driver chamber with batting or fiberglass.
Here is the predicted response situated in a corner of a room (driver face 20 in from left and right walls) sitting on a 24 in tall stand, with moderately absorbing walls and floor:
I think it looks pretty good with 42 Hz (-3dB) bass extension and about 88dB sensitivity. It takes it down from the native 95dB sensitivity of the FE167E, but for some applications with more than a fleawatt amp, should be OK.
Concerns that the DNA box may be a little small and that the bass gain from the horn may not be enough are true. However, it is not totally a lost cause if you are willing to use the DNA in a corner and use a BSC to sacrifice some sensitivity. I made the internal width of the whole speaker wider by 2.5 inches (10.5 in wide internally) and added a 1.2mH & 10ohm BSC. This is kind of a small speaker and it helps to raise it off the floor on a 2 ft tall stand which places the driver height at about 40 inches and helps to reduce a floor bounce cancellation. Also, add light stuffing in the channel immediately after the round throat, and a light amount in the horn channel at the bottom 'gooseneck' where it goes down up and down. No stuffing in the long passage from top to bottom or the mouth area. Line 3 of the walls inside the driver chamber with batting or fiberglass.
Here is the predicted response situated in a corner of a room (driver face 20 in from left and right walls) sitting on a 24 in tall stand, with moderately absorbing walls and floor:
I think it looks pretty good with 42 Hz (-3dB) bass extension and about 88dB sensitivity. It takes it down from the native 95dB sensitivity of the FE167E, but for some applications with more than a fleawatt amp, should be OK.
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After widening the cabinet to 10.5 inches, it fits easily enough and is no longer shoehorned in. I think that gain in bass could be better if a larger box was used, but for such a compact enclosure, 88dB and 42Hz may be acceptable for some people (I would like it, for one). It was easy enough to mod the original model to sim this. The biggest reason why one would be interested is someone already has these drivers in-hand and has been looking for a home for them.
I did a few for the FE series some years back for the FH site -we took them down at the start of last year given that the drivers were discontinued some time ago. A whole new set for the FFxxxWK series were worked up just after those units drivers were released, & are lurking in the electronic wings to be drawn up. They've not been a priority though. Perhaps the time is slowly approaching. Possibly. Depends if anybody's interested TBH.
As far as small BLH are concerned, there are already several yeoman designs for the 3 - 4" and 6" class of FR drivers that the 167E would have slotted into.
As already noted, if the question is relevant to an owner of existing drivers, there are designs for the 167E that work well enough. Few folks have built every possible topology - I've only ever done small BRs and the Floorstanding Fonkens for this driver.
If compact size required, there was something called a Chili & Half Chili for which Dave has archived drawings IINM.
While IIRC they were originally front mouth, presumably, it wouldn't be too difficult to reconfigure the enclosure to reverse that?
As already noted, if the question is relevant to an owner of existing drivers, there are designs for the 167E that work well enough. Few folks have built every possible topology - I've only ever done small BRs and the Floorstanding Fonkens for this driver.
If compact size required, there was something called a Chili & Half Chili for which Dave has archived drawings IINM.
While IIRC they were originally front mouth, presumably, it wouldn't be too difficult to reconfigure the enclosure to reverse that?
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Thank you, much appreciated. Gain from the horn is not the primary goal - the horn loading of the port largely takes away the narrow tuning that a standard BR has.
Others: Yes I have three lightly used drivers on hand. Linen surrounds have proven to have a long life expectancy in contrast to a foam surround that has a bad reputation.
I have been searching for a design that goes low enough to use without a sub and will fit into a difficult spot. This is a design with a shape that may fit the requirements.
PS Any idea what cone excursion will be like?
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I believe you've spoken previously about the reputed shorter life span of foam surrounds - while there's no question this was the case in the past,(70's-80's for sure) do you have personal experience or anecdotal reports with it an issue more recently? To be honest, while not consciously a factor in any of my calculus, I can't recall owning any commercial product other than perhaps Advents in the mid 70s with foams, and being at that time a charter member of the upgrade of the month club, I certainly would never have owned anything long enough for the foams to rot out.( or for that matter for the new car smell to fully "vap" off.
This is not to denigrate the 167E - still a fine driver, but some folks might take its mention as the opportunity to discuss the general topic of whizzers cones.
This is not to denigrate the 167E - still a fine driver, but some folks might take its mention as the opportunity to discuss the general topic of whizzers cones.
Plastics that have a 10 year life span in Europe have a 1 year to 18 month lifespan in New Zealand due to high UV and less pollution in the sky.
Quality foam used for materesses still loose approx 10% of their weight each year.
Locally I know of one case that foam started to disintegrate after approx 4 years.
I've had some National Panasonic drivers that were from 1972 that have linen surrounds and were still working fine.
Have just been caught with some Monitor Audio drivers from 1995 that had dried out rubber surrounds.
I have little doubt that the sound quality and performance has been improved but at what cost? The older Fostex drivers had solid steel baskets, look at the thin stuff these days and that rings like a bell.
With having to commision the build to someone else I am just not taking the chances that the foam is gone in 5 ~ 10 years, especially if there is no-one locally who is capable of re-doing a surround. This is also why I am not interested in the original W5-1880 driver since it has a foam rubber surround.
The $ 0.98 trick will take care of the whizzer cone issues.
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You are welcome. I will take a look at the excursion when I get to my AkAbak computer. As I recall it is about 0.5mm at 2.83v around 40Hz and goes into runaway below that. If your music doesn't have sub 40Hz content and you use small amps should be fine. The horn loading is not so great as this is a hybrid reflex BLH with a rather large driver back chamber.
Regarding foam surrounds. I have a Boston HD5 from 1995 that lasted about 12 yrs before the foam crumbled into dust. I have a sub woofer from same period with foam surround and it lasted 10 yrs. my wife has some JVC speakers from 1992 with rubber surrounds and they are still working perfectly today (both the full range tops and the sub woofer).
My experience tells me to not get another foam surround speaker. I will make enclosures out of foam but I will pass on foam in the driver surrounds
I'm with Amadeus Mozart regarding cloth surrounds. There is a reason most pro audio drivers use treated cloth: it is durable and designed for continuous use.
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Vifas are rubber IINM
The doping materials in treated cloth surrounds are susceptible to drying out and in some cases stiffening significantly enough to substantially alter the drivers TS parameters
But your concerns over foam are noted - and perhaps it's more of a global problem than I realized. For some reason I'd been given to believe that material chemistry had improved since the 70s, and that foam rot was less of an ongoing issue.
Perhaps a poll of folks who've had repeat failures would be in order? - like I said earlier, even though my turnover rate has slowed down somewhat in the last 20yrs, , I've probably still never owned anything long enough for that type of failure, and probably have a myopic view on the subject.
The doping materials in treated cloth surrounds are susceptible to drying out and in some cases stiffening significantly enough to substantially alter the drivers TS parameters
But your concerns over foam are noted - and perhaps it's more of a global problem than I realized. For some reason I'd been given to believe that material chemistry had improved since the 70s, and that foam rot was less of an ongoing issue.
Perhaps a poll of folks who've had repeat failures would be in order? - like I said earlier, even though my turnover rate has slowed down somewhat in the last 20yrs,
, I've probably still never owned anything long enough for that type of failure, and probably have a myopic view on the subject.But back to Amadeus' original question - as you apparently have the FE167s, are there particular constraints to cabinet size that drew you to think of the DNA horn? I built a pair of those with the small TangBand, and the combination works quite well- although the driver's pricing is unfortunate. However, having built several pairs of enclosures for the Fostex, ( still have a pair of the floorstanders Fonkens in my collection, and both my sisters have them in their systems), I think there might be a more suitable design extant that wouldn't require major re-engineering.
I think it is more a case of what are your priorities - for each individual they might be different. I just do not want to keep on changing stuff.
Regarding your other question - I love the metronomes and I have the FF105WK metronome sitting on my desk and the FF125WK metronomes in the lounge.
Unfortunately metronomes for the FE167e get too tall (not to mention a more time consuming, or $$$ when done by third party, build).
I was attracted to the XL FH but unfortunately it will not fit in the designated lounge area (too deep).
The FE167e deserves something better than a simple BR or ML TL and I've been thinking about Bob Brines folded Voigt and port it to the back instead.
At the moment I am waiting for the FE127e folded monopole to be completed - one design change has been made and that was extending the divider to the bottom and dropping the driver down to 0.349 * total line length. Baltic birch is difficult to find locally and I get Fijian Kauri instead. (a bland, stable and rather soft hardwood that machines well - can be viewed in the same league as pine) Depending on what I finally do with the 167 these either go on my desk or on some bookshelves in the lounge.
So you are looking for more of a "bookshelf" sized speaker then? At 28 in tall, the DNA's are not exactly bookshelf or desktop size.
Here is the excursion for the FE167E at 2.83v - as long as you don't have content below 40Hz you should be OK:
I played around with the round throat dia from the driver chamber to the main horn and it doesn't do anything to increase it beyond 2.5 in. As you decrease it, the slope of the bass roll off becomes more gradual and bass extension is deeper but depressed. Very bass reflex like in behavior. It doesn't change the cone excursion much.
Here is the excursion for the FE167E at 2.83v - as long as you don't have content below 40Hz you should be OK:
I played around with the round throat dia from the driver chamber to the main horn and it doesn't do anything to increase it beyond 2.5 in. As you decrease it, the slope of the bass roll off becomes more gradual and bass extension is deeper but depressed. Very bass reflex like in behavior. It doesn't change the cone excursion much.
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Thanks a lot for these details.
In the lounge it can be a floor stander.
The desk is L-shaped and runs along two walls, corner to corner. Could flip them upside down to get driver more at ear height. Although in a real venue normally you will be looking up to the venue as well (if you are in the front row).
I won't be having deep bass, I am not into head banging or movie explosions but am concerned about xMax. Hence that I started to look at horns, e.g. the BK-161 (later version of the BK-16 with larger coupling chamber) but those have some large SPL (20 dB +) swings in mid bass which will be audible.
Never saw a comparsion of excursions between ML-TL, Voigt and BR and I wonder if a folded Voigt would be better in this regard. Have you read anything anywhere?
Perhaps a DCR would work?
A more compact cabinet with a decent response can be had using a dual chamber reflex (DCR). Here is a 31 liter design for the FE167E that is 8.5 in wide x 14.0 in deep x 18 in tall (internal dims not including exterior walls or middle divider). The divider separates the volumes in a 2:1 ratio with the larger one on top where the driver is located and the lower one on the bottom. Each chamber uses a 50 mm dia x 114 mm long vent that is rear facing, the inter-chamber vent is a 50 mm dia hole cut through the 12 mm thick divider panel. Bass extension with this design is about 44Hz (-3dB) with about 90dB sensitivity. It requires a 1mH+7ohm BSC circuit to tame the baffle step loss. In reality, the stuffing or damping in the chambers will significantly reduce the mids and HF's from leaking out and causing those peaks at 600Hz and 1100Hz - so ignore them. To get an idea of what this speaker might look like, check this thread: http://www.diyaudio.com/forums/full-range/252627-viva-la-vifa-curvy-cabinet-dcr-tc9fd.html. A curvy cabinet will help reduce resonances but is not mandatory.
Here is SPL vs Freq at 2.83v:
Here is cone excursion at 2.83v:
A more compact cabinet with a decent response can be had using a dual chamber reflex (DCR). Here is a 31 liter design for the FE167E that is 8.5 in wide x 14.0 in deep x 18 in tall (internal dims not including exterior walls or middle divider). The divider separates the volumes in a 2:1 ratio with the larger one on top where the driver is located and the lower one on the bottom. Each chamber uses a 50 mm dia x 114 mm long vent that is rear facing, the inter-chamber vent is a 50 mm dia hole cut through the 12 mm thick divider panel. Bass extension with this design is about 44Hz (-3dB) with about 90dB sensitivity. It requires a 1mH+7ohm BSC circuit to tame the baffle step loss. In reality, the stuffing or damping in the chambers will significantly reduce the mids and HF's from leaking out and causing those peaks at 600Hz and 1100Hz - so ignore them. To get an idea of what this speaker might look like, check this thread: http://www.diyaudio.com/forums/full-range/252627-viva-la-vifa-curvy-cabinet-dcr-tc9fd.html. A curvy cabinet will help reduce resonances but is not mandatory.
Here is SPL vs Freq at 2.83v:
Here is cone excursion at 2.83v:
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A well designed MLTL or Voigt pipe will load the cone better so should be able to handle more power. A well design BLH or a scaled K-15 (6th order bandpass) will have the smallest cone excursion and highest power and SPL output. A scaled K-15 can be even better than a sealed cabinet in terms of cone movement control.